Disclosed is a method of electronic printed circuit board and module design which allows for several levels of automatic diagnostic analysis and subsequent identification of potentially bad modules when the main board fails first level tests.
1. Description of the Prior Art
Modern printed circuit boards in electronic equipment are designed to provide adequate access for tests of the assembled board itself. However, when these assembled boards fail tests, they then require an added level of manual diagnostic testing, performed by a technician at another test position. This technician must be trained in the proper functioning of the circuitry of the board, and typically may require a substantial period of time to perform the trouble diagnosis by confirming the failure of the unit and determining its probable cause.
It is known in the prior art to modularize particular functions of electronic devices, such as radio transceivers, in order to miniaturize the physical size of the device package as required, for instance, in field applications. For example, U.S. Pat. No. 4,792,939 to Hikita et al describes modularizing the duplexer and its functional subcircuits as well as the power amplifier of a radio transceiver in order to drastically reduce the volume occupied by the device.
A problem with the modular construction of the printed circuit boards of the prior art, however, is that they typically contain functional circuitry which, as assembled on a board, cannot be independently tested as individual or unique functional building blocks of the device. One functional building block, for example, may be spread out over several modules or discrete elements of circuitry. Moreover, there are no known methods for designing functional stand-alone circuits which can be tested on or off the board as individual functional modules.
A need in the prior art therefore exists for a printed circuit board having modules of circuitry making up discrete functional building blocks of an electronic device where the blocks can be tested as stand-alone modules for unique functions either on or off the circuit board.
2. Summary of the Invention
Disclosed is an apparatus and method of modular electronic printed circuit board design for a radio communications transceiver in which the electronic circuitry forming the functional building blocks of the device is individually modularized to facilitate independent stand-alone functional testing both on and off the board.
In an exemplary embodiment, a transmitter/receiver board uses modular circuitry for the major functions of the transmitter and receiver in such a manner as to provide access for automated tests and diagnostics of the board modules when tests of the board indicate a failure to obtain acceptable product specifications. Preferably, each module is designed to contain all of the circuitry needed to perform each major or unique function of the exemplary radio transceiver.
The board preferably has test connections accessible from the bottom of the board for "pressure pin" contacts of the automatic test equipment. Each of the module's input and output connections are directly accessible from the bottom of the board or via through-hole connections on the board.
The modularity feature not only permits module testing prior to mounting on a board, but also allows the completed boards to be automatically tested and diagnosed to a degree where it can be determined which, if any, module has failed. Thus the feature provides access to the board for testing and also provides for a second level of test and diagnostics not found in the prior art.
The exemplary embodiment of the present invention also eliminates the need for a specially trained technician to diagnose the cause of test failures, which further eliminates the need to invest in the additional test equipment such a technician would require to diagnose the cause of many kinds of failures.
Additionally, the exemplary embodiment of the present invention provides fast and repeatable automatic diagnosis of test failures, and determines the module which most likely caused a given test failure. Such determinations and subsequent module replacement will thus allow increased yields for the completed transceiver boards and reduced manufacturing costs.
By designing the printed circuit boards to utilize modular circuitry of the nature disclosed, the automated test systems are then able to project the cause of the failure without the additional human intervention that is present with other products. Moreover, failed circuit boards are easily repaired, thus increasing the yield of usable boards.